Biodegradable hydrogels formed by photocrosslinking dextran-maleic acid monoester hydrogel precursor are described in U.S. Pat. No. 6,476,204. These hydrogels are pH sensitive but are not temperature sensitive, i.e., their volume and structure are not affected by temperature change.
Temperature sensitive hydrogels are known. The most widely studied of these are poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. These hydrogels have been indicated to exhibit a lower critical solution temperature (LCST) at about 33° C. PNIPAAm hydrogels are non-biodegradable.